A wide variety of cameras are known that automatically and semi-automatically adapt the operation of the camera so that the camera can capture an image using exposure settings, focus settings and other operating parameters that are most appropriate for capturing an image under prevailing scene conditions. These cameras enable even novice photographers to capture high-quality images and thus these cameras have greatly contributed to the popularity of photography.
In many of these cameras, the content of a photographic scene is analyzed prior to the capture of an image using any of a variety of algorithms. These algorithms apply various assumptions about what a user would likely find to be important elements of a scene in order to determine camera settings and other operating parameters to be applied during image capture.
For example, some cameras attempt to determine an area of importance in a photographic scene using information from an optical or other type (e.g. ultrasonic) of rangefinder and to make camera focusing adjustments based upon this information. Such a rangefinder typically determines a distance from the camera to one or more areas of the scene and applies algorithms identifying an assumed area of importance in the scene based upon the distance information. The algorithms used by such a range finder use the distance from the camera to the to the assumed area of importance as a focus distance for focusing a motorized lens system. A wide variety of such rangefinders are known to those of skill in the art. For example, U.S. Pat. No. 5,440,369 entitled “Compact Camera With Automatic Focal Length Dependent Exposure Adjustments” filed by Tabata et al. on Nov. 30, 1993, the disclosure of which is herein incorporated by reference, discloses one such rangefinder.
Other image capture settings and operating parameters can be determined where the area of importance in the scene is known. For example, exposure settings can be adjusted to provide an exposure level that is appropriate for capturing an image of the area of importance with an appropriate level of exposure. This is particularly useful in backlighting situations.
It will be appreciated that the effectiveness of many of such algorithms can be enhanced where there is a positive indication from the photographer as to what portions of the scene comprise an area of importance. Therefore, there is a need for a way to automatically determine from a photographer's actions which area of a photographic scene is an area of importance so that a camera can accurately determine image capture settings and operating parameters.
A variety of digital and non-digital image capture devices are known which attempt to discern which areas of an image of a scene are of importance to a photographer using eye gaze information. For example, U.S. Pat. No. 5,765,045, entitled “Camera Capable of Detecting Eye-Gaze” filed on Jun. 7, 1995, by Takagi et al. and Japanese Publication, No. JP 2001-116985, entitled “Camera With Subject Recognizing Function and Subject Recognizing Method” filed by Mitsuru on Oct. 12, 1999, discusses the use of the eye gaze monitoring devices in the viewfinders of the cameras described therein. The cameras described in these publications are automatic focus cameras that utilize multi-spot range finding techniques that divide a photographic scene into a plurality of spots or regions and determine a distance from the camera to each spot. The output of the eye gaze monitoring devices described therein is used to help the camera determine which of these spots are most likely to contain the subject of the image and to focus the camera to capture images at a distance that is associated with the determined spot.
The use of eye gaze monitoring has also been discussed in the context of image compression in digital imaging systems. For example, U.S. Pat. No. 6,252,989, entitled “Foveated Image Coding System and Method for Image Bandwidth Reduction” filed by Geissler on Dec. 23, 1997, discusses a technique termed “foveated imaging” in which an observer's eye gaze position is monitored in real-time and communicated to a real-time image capture system that compresses the image to maintain high frequency information near the observer's point of eye gaze and discards high frequency information in regions that are not near the observer's point of eye gaze.
Thus, cameras are known that are adapted to monitor eye gaze and use information from eye gaze monitoring equipment to make decisions about the photographic or video imaging process.
It will be appreciated that while in many circumstances eye gaze monitoring may provide an indication of which elements in images are important to a user, in other circumstances, eye gaze information may not directly indicate which elements in images are important. For example a user can fixate on an object during composition in order to ensure that an image is composed to reduce the appearance of the object in the image. Accordingly, cameras that rely upon eye gaze direction to make decisions in the image capture process may make these decisions based upon erroneous assumptions about which elements of the image are important. Better imaging decisions can be made using eye gaze information during post capture image processing where more information about the user, the scene and/or the elements of interest are available and where more time and more complex image processing algorithms can be applied to better interpret eye gaze information.
Commonly assigned U.S. patent application Ser. No. 10/303,978, entitled, “Digital Imaging System With Eye Monitoring” filed Nov. 25, 2002, by Miller et al. describes an image capture system having an eye monitoring system that stores eye information including eye gaze direction information during an image capture sequence and associates the eye information with an image captured during the image capture sequence. In certain embodiments, context information is also captured with the eye information. The context information is also associated with the image. The eye monitoring system described therein is useful for its intended purpose, has commercial value, and has broad application. However, some consumers prefer not to use eye-monitoring systems. Also, the cost of eye monitoring components may deter their usage. Additionally, eye monitoring systems are known to need calibration for each of different users.
Accordingly, what is needed is a camera and method for determining an area of importance from a photographer's action, in composing a scene so that image capture settings and other operating parameters can be adjusted based upon this information.